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