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