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