The ornamental design for a toweldispensercover, as shown and described.
1. Towel dispenser cover
1.1 : Top Perspective
1.2 : Alternate Top Perspective in Environment of Use
1.3 : Bottom perspective in Environment of Use
1.4 : Bottom
1.5 : Front
Design no. 1 shows a paper towel dispenser cover, wherein the broken line circular and rectangular hatched features do not form part of the claimed design can be seen in place of the selected logo. The broken lines showing portions of the towel dispenser cover and environment of use also form no part of the claimed design.