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