at the risk of more thread creep into theory - this diagram by Roy de Maistre, an Australian painter of the mid 20th century - shows his correlation of a colour for each note of the scale:

colour music scale

as well, in some cultures (indian - hindu, for example) each note was attributed to a god or goddess, which gave it a corresponding colour, emotional quality, a planet, climate, day, hour; and every tone had a specific animal quality. all this was defined so that Hindu music has layers of understood meaning beyond the sound, it plays in colour, philosophy and myth.

I learnt some elementary aspects of Hindu sound and colour through meditation (on sounds and colours) and simple Bangali songs.

freda