I believe that each company had their own uniform, but the styling may have been similar.

This is for the Des Arc Rangers:
April 5, 1861; The Constitutional Union (Des Arc, Arkansas.)
This corps, at their last meeting, adopted as their name, The Des Arc Rangers. On last Saturday they paraded through our streets, for the first time, in their uniforms, presenting quite a soldier-like appearance. The uniform adopted by the Rangers is a red flannel shirt, with a deep blue breast and back, blue cuffs and black velvet collar, with three rows of brass buttons in front; black pants, with red stripes up the sides; United States cavalry fatigue cap, with ostrich plume, with colt’s Navy repeaters and United States dragoon sabers.

I saw a picture of a 1st Ark. Mtd. Rifles soldier with this same uniform except his shirt was plaid flannel. I have misplaced the photo though. It was a carte d' visite and the soldier was very thin. I want to think that I saw it on the General Sweeny Museum site.