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