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