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