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