See Plotting options in Python for general information about plotting Clawpack results. GeoClaw results can be viewed using these same tools. Some addition functions and useful colormaps are available in the module $CLAW/python/pyclaw/plotters/geoplot.py
In particular, the following functions are useful to specify as plot_var attributes of a ClawPlotItem (see the module for more documentation):
topo, land, depth, surface, surface_or_depth
The function plot_topo_file is useful for plotting the topography in a file of the type described in Topography data.