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