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