I'm assuming the others are supposed to represent other marginalized groups.

Brown for people of color, pink for women, though your guess is as good as mine on the purple.

The idea of intersectionality is that it is not feasible to try to uplift one marginalized group to the exclusion of others, so it's basically saying "we have each other's backs regardless of race/gender/sexuality/whatever purple is."

Would not surprise me if this was an AI generated shirt though, or at least a ripoff of an original design someone else made, because I've seen this same sort of design everywhere.