To answer your question though, Navis wears a yellow blouse, then tan suspenders, and then their cloak over it, with the black tie being part of the cloak. Without the later, they would probably look just about how you would imagine, with more of their sleeves showing and the suspender straps going over their shoulders.
Also, I think Navis wear the same shoes throughout the whole game (blue sneakers)... if they don't, it's likely a spriting error on my end lol