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