The ornamental design for a toilet paper cover, as shown and described.
FIG. 1 is a top, front, and left side perspective view of a toilet paper cover showing my new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a front elevational view thereof; and,
FIG. 4 is a left side elevational view thereof, the right side being a mirror image of that shown.
The broken-line disclosure of portions of a wall and toilet paper holder in the views is for illustrative purposes only and forms no part of the claimed design.