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