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