Basically, if it was a dwarf/animal/whatever just doing their business = town (green)
(the "good" guys)
If a dwarf/animal/whatever was acting detrimental (i.e. moderate to heavy sabotage) to the ongoing of the fort = mafia (red)
(like, if you accidentally dig into the ocean and the miner drowns, he was clearly trying to kill most everyone in the fort, therefore mafia)
(minority wanting control over the situation by means of killing off those who oppose them)
werebeast/river/actively trying to kill everyone (i.e. extreme sabotage) = SK (serial killer) (yellow)
(wants everyone but themselves dead)
poor schmuck trying to flee a dangerous situation just to get killed = survivor (yellow)
(just wants to stay alive, doesn't care who's in charge)
idiot wandering off and looks like they are trying to get killed = jester (yellow)
(actively trying to get killed)
idiot wandering off to try and get killed out of sight = martyr (yellow)
(actively trying to get killed but not really publicly so)
group of people acting all creepy together = cult (yellow)
(like mafia, but they convert people from the town rather than kill them off)
dwarf seemingly trying to just get one other dwarf killed (maybe in a tantrum) = lyncher (yellow)
(sole goal of killing one particular target in a more public way)
dwarf seemingly trying to just get one other dwarf killed (in a secluded manner) = assassin (yellow)
(sole goal of killing one particular target in a more hidden way)
jerkass dwarf just standing around watching things happen = watcher (yellow)
(sole goal of surviving for a set amount of time)
dwarf trying to help out one of the non-town roles fulfill their goal = [role]-Ally (matching color to [role])
(wins when their target person wins, but not technically the same role as their target)
dwarf doing something inexplicably weird when they die = outsider (yellow)
(everything else)
Town (green) is going to be 80%.
Mafia (red) is going to be like 15%.
Everyone else (yellow) is going to be like 5%.
That's probably a good quick and dirty Mafia<->Dwarf Fortress translation.