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