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