The Somersetshire Miltia has red coats lined yellow, we know this as they are recorded as being discarded by some of their members and picked up by the rebels.
According to Christopher Scott's The Armies & Uniforms of the Monmouth Rebellion, you could use the following.
Apparently there are references to the Devon and Cornwall Militia having green coats and the Hampshire Militia having yellow. Wiltshire probably had red coats but a 'blew regiment' may have been a reference to coat colour.
Miltia regiments typically were issued with a coat but breeches, hose and hats were probably the ordinary wear of the owner. Allows you to differentiate militia with a nice miscellany of colours for nether wear.