The ornamental design for the foam/sponge hair roller cover, as shown and described.
The FIGURE shown is a top, front perspective view of the foam/sponge hair roller cover according to the invention. The bottom, rear perspective view is a mirror image thereof.
The diagonal lines along the top and bottom of the cover represent machine stitches and form a part of the claimed design. All other broken lines are shown for illustrative purposes only and form no part of the claimed design.