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