I think Zapata westerns are a reasonably reliable guide; from what I've seen their research seems to have been quite adequate, so take a look at 'Villa Rides' and others of its ilk.
The costume designer for 'And Starring Pancho Villa as Himself' seems to have gone for a deliberately stylised, drab, washed-out look for the revolutionaries, who consequently mostly seem to be effectively in light khaki.
The rest is just a matter of looking at period photos and applying common sense.
I went with mostly drab shades for my Villistas jackets and trousers: assorted browns, red-browns, tans, greys, grey-browns, blue-greys, and grey-greens, with some understated dark or dull blues and greens, and felt hats in various shades of brown, tan, grey, grey-brown and black, (think Boers with a touch more colour). Shirts, where visible, can be almost any colour, but with white/off-white predominating. Any clothing items, but most commonly shirts and trousers, could be striped, usually vertically.
Zapatistas (peons) are in white/off-white shirts, and trousers mostly in the same range, with some of the latter in tans and grey-browns. Sashes were painted in brighter shades such as red and green.
Straw hats on all types were painted in a range of light khaki/sandy shades dry-brushed with a pale cream shade.
