From its earliest incarnation, Star Trek has used its distinctive uniforms to help stand apart from other science fiction epics. Over time, they became as important to the franchise as the phasers and transporters: particularly the unique "tricolor" patterns of red, blue and yellow. Every series has its own version, and the specific designs vary as a way of making each series distinctive.
Source：https://www.cbr.com/star-trek-uniform-color-meaning/
