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