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