Color points on a map concerning different values in a column

You just have to map that variable to the colour aesthetic, with something like this

geom_point(data = df1, aes(x = LONGITUDE, y = LATITUDE, colour = ACTOR1), size=1, alpha=0.5)

If you need more specific help, please provide a minimal REPRoducible EXample (reprex) including sample data on a copy/paste friendly format as explained in the link provided.