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