One vertex per element, one color per generator, with an edge from x to x·s.
(2,4)(14,18)(15,21)(16,23)(19,26)(20,24)(25,27) involution — undirected(1,2,3,4)(5,6)(7,11)(8,10)(9,12)(5,7)(6,9)(8,12)(10,11)(13,14,17,20)(15,19,21,27)(16,24,23,18)(22,26,28,25)(7,12)(9,11)(13,15,17,21)(14,19,20,27)(16,22,23,28)(18,25,24,26)(6,10)(9,11)(15,21)(19,27)(22,28)(25,26) involution — undirectedA 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.