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