Color code individual characters on pages you view -- induce color-graphemic synesthesia
A study by scientists in the Netherlands has shown that it may be possible to induce color-graphemic synesthesia (viewing letters as having an innate color) by reading text containing letters with a consistent color coding.
Replicate their experiment at home with the Synesthetize extension. Synesthetize can be configured to color as many or as few letters as you want in the colors you prefer, so you can use existing associations for a stronger effect.
Read the study that inspired the extension: http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0039799
Source available at: https://github.com/gsavvas/Synesthete