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