I am interested in the color scheme, because the Golden Dawn was incorrect in assuming that all colors could be mixed from a single choice of red, yellow, and blue. The only three colors that have the theoretical possibility of producing a large gamut of strong colors are cyan, magenta, and yellow, which are used in printing. However, until fairly recently, a good magenta pigment suitable for paints was not known, and the Wendrichs wanted to design the cards as oil paintings. Now several quinacridone colors have been produced which are suitable for magenta pigments, and I assume that this was incorporated into the color scheme for the Tarot deck.
I have the deck, which I think is the very best of all the GD decks artistically. The book is not in my budget yet, but I intend to get it.