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