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