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