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