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