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