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)(15,23)(16,25)(17,22)(18,24)(19,20)(21,26)(27,28) involution — undirected(1,2)(3,4)(6,10)(11,12)(13,15,18,19)(14,20,24,23)(16,26,27,22)(17,28,21,25)(2,4)(13,16,19,26,18,27,15,22)(14,21,23,25,24,17,20,28)(1,2)(3,4)(5,7,9,8)(6,11,10,12)(13,17)(14,22)(15,25)(16,23)(18,21)(19,28)(20,27)(24,26)(2,4)(5,8,9,7)(6,12,10,11)(13,15,18,19)(14,23,24,20)(16,22,27,26)(17,28,21,25)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.