I claim the ornamental design for an adult toy cover, as shown and described.
FIG. 1 is a top perspective view of an adult toy cover, showing my new design;
FIG. 2 is a right side view thereof;
FIG. 3 is a left side view thereof;
FIG. 4 is a front side view thereof;
FIG. 5 is a rear side view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The broken lines shown in the figures are for the purpose of illustrating portions of the adult toy cover, which form no part of the claimed design. The dot-dashed lines are directed to boundary lines, which form no part of the claimed design.