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