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