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