[ross hamilton hill]

This is a bit off topic but follows on from Rimbaud's poem and it's ideas.
I don't think vowels have colours when in words since the consonants frame words (except 'I', 'a', and 'Oh') and the pronoun 'I' and the article 'a' are used so often that I can't asociate any colours with them. If you tried to assign a colour to a word you'd probably drive yourself mad.
Van Gogh was interested in the correspondence between notes (in his case on the piano) and colours. This sort of correspondence is common in Western occultism, and you can see lists in books on Western magic relating colours to signs, emotions, sephorith and gemstones etc. Baudelaire was interested in these and wrote a poem called 'Correspondences'
Some people see sounds (particularly music) as colours and shapes. But I don't know if there is any consensus in how sounds are perceived and with words it would depend on the tone of voice.

ps sorry I did want to copy Baudelaire's poem (and it's translation) but couldn't. It's on the net, worth a look.