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