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)(13,14,19,24)(15,20,16,21)(17,22,26,28)(18,23,25,27)(5,7)(6,9)(8,12)(10,11)(13,15)(14,20)(16,19)(17,18)(21,24)(22,23)(25,26)(27,28) involution — undirected(1,2,3,4)(13,16,26,25,19,15,17,18)(14,21,28,27,24,20,22,23)(6,10)(9,11)(13,17,19,26)(14,22,24,28)(15,18,16,25)(20,23,21,27)(7,12)(9,11)(13,18,26,16,19,25,17,15)(14,23,28,21,24,27,22,20)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.