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