Sonardome

I don't know for sure about subs. But on surface ships they are made of rubber (by Goodyear) and are tire black. I would assume the same for subs since they need to pass sound waves, hence the rubber.

Modern American nuclear subs sonar (bow) domes are usually painted one of two ways. Either all black or the half & half combo of black above and anti-fouling red below. The all black scheme seems to be the current method.

Go to www.navsource.org and click on Philadelphia (SSN 690) or Greenville(SSN 772) for examples. On other nations I'll have to do some research.

I should have specified this is a Russian attack sub, Kilo class. Sorry.

I have seen color pictures of Kilos with their upper sonar area painted in what appears to be silver or light gray but I also have seen color pictures of Kilos with their upper sonar areas blacked out (either by sensors) or just painted black.
www.hazegray.org
Search "Russian Navy" photo section on Kilos.
For what it's worth, in Providence, RI we have one of the last surviving Juliett class submarines. Assuming they have restored it accurately, you might be able to get a better idea of the color by looking at this vessel. It's probably a standard color.
www.saratogamuseum.org

Thanks breezely, I will check that out, ummmm...soon as I was the dishes. (wife's giving me that look)