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