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