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