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