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