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