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