One vertex per element, one color per generator, with an edge from x to x·s.
(2,3)(5,6)(7,11)(8,9)(10,12) involution — undirected(1,2,4,3)(5,6)(7,10)(8,9)(11,12)(13,14)(15,24)(16,20)(17,22)(18,27)(19,23)(21,26)(25,28)(6,9)(10,11)(13,15,19,16)(14,20,23,24)(17,26,18,25)(21,22,28,27)(5,7,8,12)(6,10,9,11)(13,16,19,15)(14,21,23,28)(17,26,18,25)(20,22,24,27)(1,3,4,2)(13,17,19,18)(14,22,23,27)(15,25,16,26)(20,21,24,28)A Cayley diagram is a choice, not a fact about the group. Another drawing of this group — in a book, or on a different generating set — may look nothing like this one.