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