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