Be also aware that colours can change if a body has an high eccentricity orbit (i.e. the orbit is an elongated ellipse), as the surface conditions undergo (strong) variations during the orbit. Therefore, also the colonization cost of that body changes at the different zones of the orbit.
Mercury shows this variation, and it's rather easy to observ thanks to its short orbital period (in this moment, in my game, CC for Mercury is 2.46 and the colour is light blue, against the situation of Nuclearslurpee, where it is brown at 3.38).
Be aware too that things depend on the settings of your race. If you set large or small ranges of environmental compatibility for it, colours can be very different from the ones shown in the image posted by NS.