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