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