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