Unlike the other combatants of the Seven Year War, Russian line and grenadier units had no regimental distinctions. If present, these were minor.
Basically, both musketeer and grenadiers wore a green coat with red collar and cuffs worn over a red waistcoat and breeches. Gaiters were white during the Summer period. Cartouche black and suspended from a natural leather belt. Black tricorne had white lace. Not a difficult figure to paint. but getting the right shade of red or green is the challenge.
I am aware of instances when coats were not worn during the Summer, but then so did regiments of other nations.
More information about uniforms, I would direct the reader to Kronoskaf.com for further details. Russian Musketeer uniforms:
The twelve elements are at a stage two level; basically the figure is fully covered. The next stage will bring detail to the figures and with minor cleaning up will be finished. In the background are the next batch of musketeers and grenadiers at various stages of preparation.