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