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)(13,14,18,22)(15,19,21,17)(16,23,24,28)(20,27,25,26)(1,2,3,4)(5,7,9,8)(6,11,10,12)(14,15)(16,24)(17,19)(20,28)(21,22)(23,25)(5,8,9,7)(6,12,10,11)(13,15)(14,19)(16,25)(17,22)(18,21)(20,24)(23,26)(27,28)(13,16,18,24)(14,20,22,25)(15,23,21,28)(17,27,19,26)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.