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