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