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