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