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