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