>>531427993
The colours are obviously taken from the mask and the jockey's clothing but as for why her design is so extra it's hard to say.
The horse was an eccentric character that always stood out due to his unique behavior and running style which also made him a popular fan favourite that people enjoyed watching even though he lost a lot.
Making the uma so extra is a way to show that I suppose, even years since release, she still stands out so they nailed it if that's what they were going for.