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