Man, that term befuddled me for a bit. Like, I had to ask a buddy I was in law school with what he thought about it. Graphic sex seems to come down to penetration, presentation of fluids, and straight up non-plot purpose pornographic material. So pretty much TV/HBO rules, but with a "less is more" suitability to it. When Khal Drogo drops the hog on his bride to be, we get pretty non-graphic sex. No shaft, no fluids, it is not presented for our arousal.
Sort of an important thing to look into. I mean, my comic is by no means smut; but the issue we're about to finish takes place right after sex and there's a bit of it shown (no shaft for the sex part anyway, but the guy is nude/not-erect after) and there's nudity to follow; none of which are really presented in a sexual way because the purpose is to highlight tension with the conflict that's about to come/does come--specifically from a vulnerable place of betrayal.
Of course we keep these sections behind the NSFW section; as it ought to be. I do think Tapastic ought to clarify their NSFW policies, simply because if we operate under the "I know it when I see it" mantra, there's a lot of grey area. Which can be good, or bad; clarity at least brings clarity. I mean, with the looks of some of those novels we might be getting into the realm of Ravaged by Raptors: An Erotisaurus Production showing up; which is fine if that's the market they want to get cash from. I'm not one to judge, a market is a market.