Based on what I know, the trick is to stimulate the cones in such a way that the brain perceives a given color. There are three types of cones, each with a different spectral response. I can easily imagine that, as the disk is spinning, the constrast line between the white and black would move across the retina as a front. Since the cones (receptors) are activating at slightly different times, because no two receptors are in the exact same location, then the brain perceives this phase difference as a different ratio between different receptors and color perception is generated. It is a very interesting illusion.
The interesting thing is that (from my personal observation) the illusion of color is best under monochromatic light. If you can get a low pressure sodium vapor light, try it.
If the rotation of the disk is reversed, the colors swap -- red to blue, and vice-versa.