The ornamental design for a decorative surface for shower rod, as shown and described.
FIG. 1 is a front elevational view of a decorative surface for shower rod showing our new design, the broken lines are for illustrative purposes only and form no part of the claimed design; and,
FIG. 2 is an enlarged top plan view thereof.
In view of FIG. 1, it is understood that the claimed article is of indeterminate length.