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