The ornamental design for a wastedisposaldevicecover, as shown and described.
FIG. 1 is a front perspective view of a waste disposal device cover showing my new design;
FIG. 2 is a front elevation view thereof;
FIG. 3 is a back elevation view thereof;
FIG. 4 is a right side elevation view thereof;
FIG. 5 is a left side elevation view thereof;
FIG. 6 is a top plan view thereof; and,
FIG. 7 is a bottom plan view thereof.
The stippled shading in the figures is fragmentarily shown for convenience of illustration, it being understood that the stippled shading is uniformly continued over the surface on which it appears.