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