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