Which image/video are you referring to? As far as I can tell, the colors are not used to represent race, but to convey different kinds of information. For example, in Figure 1 and 3 of the paper, the color indicates different points in time. In the video, the colors indicate different motion generation methods. I would not classify "orange", "blue" and "purple" as Caucasian, but if you want even more colors, you can have a look at the original paper where color coding was used to differentiate between different skinning methods (Figure 2).

https://files.is.tue.mpg.de/black/papers/SMPL2015.pdf