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