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