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