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