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)(13,14,17,20)(15,21,23,28)(16,25,22,19)(18,26,27,24)(2,4)(7,8)(10,12) involution — undirected(5,7,9,8)(6,10,11,12)(13,15,22,26,17,23,16,24)(14,18,25,28,20,27,19,21)(5,8,9,7)(6,10,11,12)(15,23)(18,27)(21,28)(24,26)(6,11)(10,12)(15,23)(18,27)(21,28)(24,26) involution — undirectedA 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.