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