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