in look it will be whatever, it could be a business man in a suit or a hipster look will be different. BUT i will say that if you know someone that is capable of changing thier look, over time and years and they pull it off this is strong indication they are an INFJ. i mean to the point where you would miss them even if you walked right by them,
in mannerisms, i would say INFJs rarely smile showing teeth. unless they are truly happy, most of time the INFJ is smiling for others and its a simple smile no teeth and not ear to ear.
eyes, they tend to stare, but only when they think no one is looking they will look at someone even in the eyes deeply and than break it quickly its like they will go in a trance and intense stare and then break it like nothing at all.
they will be quite and brooding in many ways, and they will be very tough to read. in most cases. but despite all this outter coldness most people will want to be around them because despite the types souls know when they near someone with a Warm and deep natured soul. thats what the infj looks like.
they could also be intense and sometimes angry. but not often.