FIG. 1 is a top and front perspective view of a shower wall according to my design; FIG. 2 is a top plan view thereof; FIG. 3 is a front elevational view thereof; FIG. 4 is a left side elevational view thereof; FIG. 5 is a right side elevational view thereof; FIG. 6 is a bottom plan view thereof; and, FIG. 7 is a rear elevational view thereof. The broken line showing of a corner wall is for illustrative purposes only and forms no part of the claimed design.