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