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