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