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