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