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