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