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