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