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