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