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