He has brown hair done up in an awesomely Young Italian Guy style, and, according to the Visual Dictionary, it's petrified to keep it in that state. He looks every bit the young gang member trying desperately to get the boss to pay attention to him.
He wears a nice long trench coat, perfect for flashing people, or for "concealing illegal chemicals for sale", according to the Visual Dictionary. Under that, it looks like an appropriately tacky lounge shirt in some weird orange shade, what look like corduroy khakis, and shiny brown shoes with "secret compartments for storing contraband".
Elan is a 'slythmonger', your basic inner-city drug dealer. Here's what the Visual Dictionary has to say about them:
"Slythmongers - low-lifes who peddle cheap narcotics manufactured by disbarred pharmacists are called slythmongers on Coruscant. A few are likely to show up at any average club. Slythmongers must be prepared for a quick exit when customers have a bad or fatal reaction to the latest, most fashionable concoction."
Lucas has decided to flesh Elan out in the Databank. Wow, wonders never cease. Rather than plagiarising, I'll just leave the link there for you all to click and peruse at your leisure!
For an idea of how he's described in the novelisation of Attack of the Clones, check out a scan of page 107; Elan's moment in the spotlight.
Unfortunately, that's about all there is to go on. The rest is just theory and speculation.