BETA PHOTO: Tanya on the final headwall of Sunday Morning.
The 5.7 grade applies only to the crux(es) which are the undercling move, and at the top, following the vertical crack in the black face. You can easily maneuver around these cruxes to arrive at the same place. An easy top-rope version would probably go 5.5 due to the roof (i.e. Sunday Morning).
15 feet to the right of the Library dihedral is a smooth orange and black slab broken by a left-to-right trending crack. This is the Sunday Morning Crack. Follow the crack up to the roof/overhand. Pull past the roof on the left. Above the roof, look for an obvious flake/undercling, and traverse left to the arete using this undercling. Follow the arete up and trend right on the next two horizontal ledges. Finish the climb with bouldery moves in the vertical crack on the black face on the center of the south-facing wall.
This is probably the best lead at Chickies. The pro is solid, and the falls are clean at all the difficult spots.
This actually describes a route called "The Undercling". Sunday Morning (5.4) continues past the overhang over easy ground to a notch and up to the top. The moves past that little roof are a bit of a sandbag at 5.4 and I don't feel the pro at the roof is great (behind thin flakes), but it's a fun climb. Other routes share this start as well, Train Wreck (5.7) goes up the center of the face after the roof, while Lower Undercling goes out to the arete via the small flake below the roof.