Do the Colours on the AVI Values Map have any particular meaning?

Yes. The colours are used to indicate the priority of your values.

From highest to lowest priority the default colours are: Navy Blue - 91 to 100%, Dodger Blue3 - 81 to 90%, Dark Green0 - 71 to 80%, Saddle Brown - 61 to 70%, Red3 - 51 to 60%, Khaki - 41 to 50%, PaleGoldenrod - 31 to 40%, Moccasin - 21 to 30%, PapayaWhip - 11 to 20%, LemonChiffon - 1 to 10%

The colours listed above are the default colours for the online AVI. It is possible for different Values Consultants to use their own colour scheme, however, the categories of priority are the same.