Data

For this example, we will use the data provided in the package sula
The data is from tracked masked boobies at Rapa Nui
The data is already in tidy format

my_data<-(sula::GPS_preparado)

color1<-'#ff595e'
color2<-'#ff924c'
color3<-'#ffca3a'
color4<-'#8ac926'
color5<-'#52a675'
color6<-'#1982c4'
color7<-'#4267ac'
color8<-'#6a4c93'

Plots

library(ggplot2)

Lets create a plot where each color is a different individual and we gave specific colors.
Note that this can also be made with scale_color_manual.
However, for the example I separate them as you might be using layers.

my_plot<-ggplot() + 
  
  geom_point(data = subset(my_data,IDs=='GPS01'),aes(x=Longitude,y=Latitude),color=color1,size=0.5,alpha=1)+
  geom_point(data = subset(my_data,IDs=='GPS02'),aes(x=Longitude,y=Latitude),color=color2,size=0.5,alpha=1)+
  geom_point(data = subset(my_data,IDs=='GPS03'),aes(x=Longitude,y=Latitude),color=color3,size=0.5,alpha=1)+
  geom_point(data = subset(my_data,IDs=='GPS04'),aes(x=Longitude,y=Latitude),color=color4,size=0.5,alpha=1)+
  geom_point(data = subset(my_data,IDs=='GPS05'),aes(x=Longitude,y=Latitude),color=color5,size=0.5,alpha=1)+
  geom_point(data = subset(my_data,IDs=='GPS06'),aes(x=Longitude,y=Latitude),color=color6,size=0.5,alpha=1)+

  theme(
  legend.position='none',
  legend.spacing.y = unit(0.05, 'cm'),
  legend.text=element_text(size=10),
  legend.background = element_rect(fill='transparent',colour ="transparent"),
  legend.box.background = element_rect(fill='transparent',colour ="transparent"),
  legend.key = element_rect(fill = "transparent", colour = "transparent"),
  panel.grid.major = element_blank(),
  panel.grid.minor = element_blank(),
  panel.background = element_blank())+
  xlab('Longitude')+ylab('Latitude')+
  theme(panel.border = element_rect(colour = "black", fill=NA, linewidth=1.5))
my_plot

Inside legend

Select the coordinates for the legend

legx<- -109.90
legy<- -27.4

Add text

my_plot_wtext<-my_plot + 

  annotate(geom="text",x= legx, y=legy-0.1, label="GPS01",color="#343a40",hjust = 0, size=2)+
  annotate(geom="text",x= legx, y=legy-0.15, label="GPS02",color="#343a40",hjust = 0, size=2)+
  annotate(geom="text",x= legx, y=legy-0.2, label="GPS03",color="#343a40",hjust = 0, size=2)+
  annotate(geom="text",x= legx, y=legy-0.25, label="GPs04",color="#343a40",hjust = 0, size=2)+
  annotate(geom="text",x= legx, y=legy-0.3, label="GPS05",color="#343a40",hjust = 0, size=2)+
  annotate(geom="text",x= legx, y=legy-0.35, label="GPS06",color="#343a40",hjust = 0, size=2)
my_plot_wtext

Add segment

my_plot_wtext +
  annotate("segment", x = legx-0.01, xend = legx-0.04, y = legy-0.1, yend = legy-0.1,color = color1,linewidth=1)+
  annotate("segment", x = legx-0.01, xend = legx-0.04, y = legy-0.15, yend = legy-0.15,color = color2,linewidth=1)+
  annotate("segment", x = legx-0.01, xend = legx-0.04, y = legy-0.2, yend = legy-0.2,color = color3,linewidth=1)+
  annotate("segment", x = legx-0.01, xend = legx-0.04, y = legy-0.25, yend = legy-0.25,color = color4,linewidth=1)+
  annotate("segment", x = legx-0.01, xend = legx-0.04, y = legy-0.3, yend = legy-0.3,color = color5,linewidth=1)+
  annotate("segment", x = legx-0.01, xend = legx-0.04, y = legy-0.35, yend = legy-0.35,color = color6,linewidth=1)

Add rectangle

my_plot_wtext +
  annotate("rect", xmin = legx-0.01, xmax = legx+0.08, ymin = legy-0.09, ymax = legy-0.12,color = color1,linewidth=1, fill="transparent")+
  annotate("rect", xmin = legx-0.01, xmax = legx+0.08, ymin = legy-0.14, ymax = legy-0.17,color = color2,linewidth=1, fill="transparent")+
  annotate("rect", xmin = legx-0.01, xmax = legx+0.08, ymin = legy-0.19, ymax = legy-0.22,color = color3,linewidth=1, fill="transparent")+
  annotate("rect", xmin = legx-0.01, xmax = legx+0.08, ymin = legy-0.24, ymax = legy-0.27,color = color4,linewidth=1, fill="transparent")+
  annotate("rect", xmin = legx-0.01, xmax = legx+0.08, ymin = legy-0.29, ymax = legy-0.32,color = color5,linewidth=1, fill="transparent")+
  annotate("rect", xmin = legx-0.01, xmax = legx+0.08, ymin = legy-0.34, ymax = legy-0.37,color = color6,linewidth=1, fill="transparent")

You can of course use the legend, but this option is for me more easy to custom and move around the plot. Moreover, it allows you to include all kinds of annotations inside the plot.

Inside legend

Data

Plots

Inside legend

Further reading