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