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