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