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)(13,14,18,16,19,22,17,20)(15,23,26,25,24,21,28,27)(5,6)(7,11)(8,10)(9,12)(14,20)(15,24)(16,22)(17,18)(21,27)(23,25) involution — undirected(2,4)(5,7)(6,9)(8,12)(10,11)(13,15,19,24)(14,21,22,23)(16,27,20,25)(17,28,18,26)(7,12)(9,11)(13,16,17,14,19,20,18,22)(15,25,28,23,24,27,26,21)(6,10)(9,11)(13,17,19,18)(14,16,22,20)(15,26,24,28)(21,25,23,27)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.