Speak of "accuracy" is, IMHO, a little premature because NASA has not yet released detailed technical informations of the SLS.
Well, from the looks of things, we know this about SLS:
- It uses an 8.4 meter diameter core.
- It has 3-5 SSME/SSME derivatives.
- Early launches could use MPS hardware scavenged from STS Orbiters.
- The boosters, at least on early versions, are the 5-segment SRBs.
- The upper stage, probably derived from either the Ares I or Ares V upper stages (or both) is powered by the J-2X.
- Later launches could use LRBs, potentially powered by Americanised NK-33 engines made by Aerojet.
Frankly, I see no reason to trust a PR-driven computer graphic for technical details of this vehicle. This is basic common sense that applies to pretty much any animation- it's for show, it isn't intended as a snappily-made engineering guide.
Based on the fact that the Delta IV, the Shuttle External Tank, and pretty much all SDLV proposals for
over 20 years have had unpainted insulation foam, I see no reason as to why this vehicle would need to be painted white.
It is a PR excersise for a computer graphic, pure and simple.
And another thing about that white paint, is it doesn't just add weight- it adds costs as well. Painting that paint onto the foam costs money, and why spend that money if doing so is unecessary?