How can I color my taxonomy term
I would use CSS for that, and adjust CSS directives through the specific taxonomy vocabulary class, as appear in DOM.

I prefer CSS instead modularity as I think it would simplify the process and probably give you faster control over what vocabulary terms get what color, and on what circumstances.

Code example:

.field--name-field-categories .field-items {color: green}


Notes:


.field-label stands for the label.
.field-item stands for each vocabulary field-item.
.field__items stands for the whole row containing each vocabulary field-item.