I just found a very useful website for figuring out coat colors on horses. (Yes I know these are pegasi, but still.)

this is the link to part 1: http://colorgenetics.info/equine/pictorial-guide-horse-colors-part-1-chestnut-bay-brown-and-black

part 2: http://colorgenetics.info/equine/pictorial-guide-horse-colors-part-2-palomino-buckskin-smoky-brown-cremello-perlino-and-smoky

part 3: http://colorgenetics.info/equine/pictorial-guide-horse-colors-part-3-red-dun-bay-dun-brown-dun-and-black-dun-grullo

part 4: http://colorgenetics.info/equine/pictorial-guide-horse-colors-part-4-gold-champagne-amber-champagne-sable-champagne-and

part 5: http://colorgenetics.info/equine/pictorial-guide-horse-colors-part-5-silver-bay-silver-brown-and-silver-black