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