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