The colors in the image on the left are from a pentad color harmony; the colors are 72 degrees apart on the color wheel like the points of a pentagon inscribed in a circle. Actually, I just made that up in analogy to the hexad harmony I read about in a book on color theory. The hexad harmony has 6 colors spaced 60 degrees apart, and since I only have 5 colors, why not invent the pentad?
The colors on the right are from a hexad harmony, but a color (cyan) is missing. I call it hexad minus one. The conventional wisdom from Pythagorean Tarot is:
The Impulse of the Pentad is unbalanced - so it may aim for the Heavens and neglect the Abyss, or aim for the Abyss and neglect the Heavens; but the Hexad balances it: as Above so Below. Thus the Hexad brings the New Dimension into the Realm of the Known and into the Cosmos.
This is what happens when I make something up and google it.