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