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