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