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