Flight suits. Take away jippers and pockets from the ENT ones, dye the denim into departmental colours reflecting The Cage
- Gold, Blue, Sandy Biege. Add a horizonal Starfleet (UESPA?) Delta and a Kelvin patch on each arm.
In TOS whenever colonists or miners are shown, they're usually in jumpsuits. I'm thinking Devil in the Dark
, This Side of Paradise
... Perhaps the rest of the Federation get Stafleet cast-offs from previous decades.