The alpha rulebook lists them as:
"● A pendant bearing the symbols of one or more of the Five
● Loose clothing, good for travel, worn in layers. Scarves and hoods are common.
● Muted, sun-faded colors."
However, if you want to wear darker colors, including blacks, you are free to do so. It's just that some people may mistake you for an exile every now and then. An Exile, however, would be required to wear the darker colors to denote their status.
Basically, don't worry about it.