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