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