I have searched but cannot find what the color codes mean when I look at my list of observations, however, it seems to be based on the following as best as I can tell:
blue = vertebrates
red = invertebrates
pink = fungus/lichens
green = plants
If this is the color code, then the species Apheloria virginiensis (millipede) is the wrong color - it shows up as blue (vertebrate) when it should be red (invertebrate). I don’t know if this is true for other species/genera or higher taxa in this category - I just know this seems out of place for my own observation.