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