Yeah, it's funny over the years manufacturers have gone away from coloring breakers. Old fuses were often color coded and I guess that just trickled to breakers. Zinsco/Magnestrip panels from the 50s era had kind of pastel colored breakers. Sylvania panels are probably the most recent to be colored but seemed to end in the 90s. I can't think if any modern day panels that have it. They are all just black. And this is all residential I'm talking about - RVs are probably similar though as far as age. Like others have said it has to do with Amp rating. You can always look closely on the ends of the switches or somewhere close and you'll see a 15, 20, 30, etc. for the amps.