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