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)(14,18)(19,27)(20,28)(21,25) involution — undirected(1,2)(3,4)(6,9)(10,12)(13,14,16,18)(15,19,22,27)(17,25,24,21)(20,26,28,23)(2,4)(13,15,16,22)(14,19,18,27)(17,23,24,26)(20,21,28,25)(2,4)(5,7,8,11)(6,10,9,12)(13,15)(14,20)(16,22)(17,26)(18,28)(19,25)(21,27)(23,24)(6,9)(10,12)(15,22)(19,27)(20,28)(23,26) 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.