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