You could go Murray, Charles or even Sproles.
It's gonna suck to have a late third RB as your RB1, but i'd be very tempted to take Graham.
Lots of question marks with all the available RBs, but Graham is almost guaranteed to have a top season and outscore your opponents' TEs big time.
Since it's PPR i'd probably take Graham. I've taking him at the 14th spot (got 3rd pick in 8-man PPR league) in almost all the mock drafts where he's fallen to me.
2012 roster (8-man PPR league)
RBs: Foster, Charles, D. Martin, Murray
WRs: J. Nelson, Fitzgerald, Bowe, Nicks, T.Y. Hilton, M. Williams
TEs: Graham, Hernandez
K: S. Graham