Dai
The disclaimer first. Still can't find any pictures. My references end Dec., 1941. All of this info is generic.
the Air Corps specified camoflage for all cargo a/c in Sept., 1940. Days later, the spec was issued for the colors to be OD 41 over Neutral Gray 43. the C-79 came on May 13, 1942 (3 years to the day before me). I'm guessing this would be your colors. 41 is a very dark green with a brownish tint. It fades to a brown. The sides of the a/c being flat, the gray would not come up the sides. Propellers and hubs were called out black.
Star in circle was the national marking, upper left and lower right wing. The size was to be 3/4 of the chord of the wing, maximum of 60 inches. It was centered front to back on the center of the chord. I'm not sure how far in. For the fuselage, it was centered between the trailing edge of the wing and the leading edge of the stabilizer. It could be moved if it would end up on a transparency. The height was 3/4 of the height of the fuselage, maximum of 48 inches.
The letters of the radio call sign were specified yellow. The width of a letter was 2/3 of the height. The distance between the letters was half the width of a letter. The brush stroke was 1 inch wide for every 6 inches tall. The call sign was on the fin in front of the rudder. If you don't have it, the C-79 serial was 42-52883, call sign 252883. I don't know what size the numbers would be. Something visible that fits the fin.
The interior color at this time was bronze green, #9. It's a guess as to whether they would have painted the interior or left it as it was. I don't know what the civil a/c were painted inside, but military was RLM 66 and maybe 02?
The a/c was given to the U. S. road service in Costa Rica in Dec., 1943 where it was called a TI-60. Hope this helps.