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