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