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