Install https://github.com/jrfonseca/gprof2dot
Install http://www.graphviz.org/
Generate a cachegrind.out file using XDebug
Generate a dot file:
$ ./gprof2dot.py --format=callgrind --output=out.dot /tmp/cachegrind.out.1360843301.16101
Create a PNG of the call graph
$ dot -Tpng out.dot -o graph.png