Here is the spectrum of visible light:
ROY G. BIV:
Red, Orange, Yellow, Green, Blue, Indigo, Violet.
Indigo is a compromise color; included here for the relative pronunciability of “Biv”; but also to achieve a one-to-one matching with the spectrum of electromagnetic radiation:
Radio, Microwave, Infrared, Visible, Ultraviolet, X-Rays, Gamma Rays
This suggests this matchup:
Red - Radio
Orange - Microwave
Yellow - Infrared
Green - Visible
Blue - Ultraviolet
Indigo - X-Rays
Violet - Gamma Rays
But there is another possibility. Visible light spans a doubling of frequencies, and violet has some resemblance to red. Perhaps colors cycle with electromagnetic frequency, just as pitch cycles with sound-wave frequency. Just as we have high C, perhaps we can have “high green” or “low yellow”. Actually the electromagnetic spectrum covers many octaves, so really you’d have “19 high green” and “26 low yellow” .