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