|(fineliner on a 139mm x 87mm postcard)|
It's not easy trying to find a nude paint-by-numbers set, especially one happily stroking her pussy! They tend to be the "chocolate-box" style image, which is never fun to paint, but at least they got more people painting and introduced many to art.
It's used here to make the viewer think more about colour, even though there's none present, not even a swatch to match the numbers with. It tries to beg the question: "What colour is her skin?" And when this happens, it begins to give the subject something of an enigmatic quality.
But many who see it will have already made their own assumptions as to her colour, for whatever reason that might be. They may even assume it so much that they'll go so far as to disregard it completely and ask: "What colour is the cat?"