OK let me suggest something to meet you halfway. As someone who is fluent/sight reading/ singing etc and can "hear" harmony and/or "read" it on a page of regular notes (lines and spaces and intervals all you really need, but to your point requires experience), something that would be far more interesting and useful to me, rather than color-coding solfege, would be something more along these lines:
Color code each chord by its diatonic value (e.g. in a I chord every note in the triad is red, in a IV chord every note in the triad is blue) and then highlight the extended notes as well (e.g. add 9 is yellow, add 11 is green)
That is something that MIGHT be interesting to me (personally - I know I am not your audience). But even thinking it through this technique sort of washes out the interesting bits of substitution/interpretation etc that you can find because you are committing to interpreting a chord with a single root
Color code each chord by its diatonic value (e.g. in a I chord every note in the triad is red, in a IV chord every note in the triad is blue) and then highlight the extended notes as well (e.g. add 9 is yellow, add 11 is green)
That is something that MIGHT be interesting to me (personally - I know I am not your audience). But even thinking it through this technique sort of washes out the interesting bits of substitution/interpretation etc that you can find because you are committing to interpreting a chord with a single root