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