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)(15,24,21,27)(16,25,20,26)(17,22,18,28)(1,2)(3,4)(6,10)(7,8)(11,12)(13,15)(14,20)(16,23)(17,25)(18,26)(19,21)(22,27)(24,28) involution — undirected(2,4)(13,16,19,20)(14,21,23,15)(17,24,18,27)(22,26,28,25)(5,7,9,8)(6,11,12,10)(13,17,19,18)(14,22,23,28)(15,25,21,26)(16,24,20,27)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.