With the early Il-2 cockpit colours is always a problem. It is suggested that it was a blue-grey paint similar to FS 36187. However we should remember that the plane appeared at the beginnning of the war. The demand for the plane was so great that factories were forced to work very quickly. Taking the shortage of proper paints at the beginning of the Great Patriotic War into consideration ... it could be possible there were cockpits of the plane painted with different paints that were just on hand. Also it can't be excluded these stayed unpainted at all. And it might have been the reason for the info the cockpit was a flat aluminum inside. I heard also about black , steel , green and light blue cockpits. The silver paint was used for pre-war cokpits of wooden planes rather. But the early Il-2 was of metal and even primers for metal structures weren't silver. In my opinion the colour scheme of the cockpit was more complex. However I would say it was more secure to follow the light blue-grey colour.