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