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)(13,14,17,19)(15,20,16,18)(22,24)(23,27)(6,9)(10,12)(13,15,17,16)(14,18,19,20)(23,27)(26,28)(7,11)(10,12)(15,16)(18,20)(21,22,25,24)(23,26,27,28)(1,2)(3,4)(5,6)(7,10)(8,9)(11,12)(13,14)(15,20)(16,18)(17,19)(21,23)(22,26)(24,28)(25,27) involution — undirected(5,7)(6,10)(8,11)(9,12)(13,16,17,15)(14,18,19,20)(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.