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