[brwagur]

When you bleach(with sodium hypochlorite) a dye, like food colors, for example, what actually causes it to lose it's color? Does oxygen disrupt the delocalization of electrons in the benzene rings? Also, what are some of the products of the reactions of bleach and
FD&C Blue No.1
FD&C Blue No.2
FD&C Green No.3
FD&C Red No.40
FD&C Red No.3
FD&C Yellow No.5
FD&C Yellow No.6
(I don't want to know the all products of every single one of these reactions, just what usually happens!)

[Yggdrasil]

You have the basic idea down.  Many dyes are colored because they have conjugated pi-bond systems which absorb in the visible range.  Bleach disrupts these conjugated pi-bond systems by oxidizing a double bond back to a single bond, decreasing the size of the conjugated pi bond system.  This results in a larger HOMO-LUMO gap and causing the dye to absorb a higher energy of light (e.g ultraviolet instead of visible).

I would guess, however, that the bleach does not oxidize the double bonds in the benene rings.  It more likely oxidizes some of the alkene double bonds in the dyes.

[brwagur]

Then does that mean that oxygen never directly bonds to the dye molecule? If not then where does that electron go? Sorry, I often get confused in redox reactions. Also, do azo dyes react slower for some reason, Yellow always seems to be the last color to disappear (and it is not the yellowish color of bleach)?