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