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