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