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