Luffy: dragon
Zoro: tiger
Sanji: phoenix
Jinbe: turtle
Starting off with Jinbe and the black turtle aka genbu. Jinbe seems to specifically specialize in hardening. Him being able to not only use full body hardening but a tougher version of normal armament in shark skin. The turtles element is also water. Fishmen in general represent black people in some ways
Next up Sanji and the vermilion phoenix aka suzaku. Pretty self explanatory but Sanji is a flying fire guy and phoenixes fly and have fire powers
Zoro the white tiger aka byakko. The tiger is associated with autumn, metal, and wind and so it zoro. Shimotsuki and therefore zoro have lots of connections to the month November. Zoro uses swords aka metal weapon and he hair air slashes
Luffy the azure dragon aka seiryu. No pun intended but this one is admittedly more of a stretch. The dragon represents wood, creativity, benevolence, and rain. Luffy being creative and benevolent is self explanatory. As for wood maybe because he ate a devil fruit with it literally coming from some magic tree somehow. For rain we’ve been told multiple times that d will bring a storm and a rain storm is a thing….idk