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