Here is a color wheel based on 10, or 9 numbers and 0. It actually has an ideal Cyan, Yellow and Magenta... but... they are not aligned in such a way as to correlate with the points of a perfect isosceles triangle, as seen in so many other color wheels. But, if one observes where the points of the inner pentacles face, they point to spaces on either side of colors that correspond perfectly with the ideal primaries and secondaries of print and light. The "Blue" of RGB is actually a Blue-Violet. The "Red" of RGB is actually a slightly Orange-Red. Even the Yellow of CMY is not supposed to be a perfectly bright Lemon-Yellow. So... even though this arrangement of colors abandons the notion of exact triangular primaries, they do exist in their usual places, which is close enough... because... it is not the goal here to create any kind of definitive color wheel of ideal colors. The goal here is to establish aesthetic rationale for associating various colors to the icons of tarot along a number line. For that, these 20 colors will do just fine!
For an alternative to these 20 colors, consult the essay Music elsewhere on this site, where these 20 colors are reduced to only 16... in order to associate 16 colors with 8 musical tones and their 8 semitones... within a 9 tone octave!!