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)(15,25)(16,21)(17,22)(18,23)(19,27)(20,24)(26,28) involution — undirected(1,2,3,4)(5,7)(6,9)(8,12)(10,11)(13,15,18,26,20,22,19,16)(14,21,27,17,24,28,23,25)(7,12)(9,10)(13,16,18,15,20,26,19,22)(14,17,27,28,24,25,23,21)(5,7)(6,10)(8,12)(9,11)(13,17,20,25)(14,22,24,15)(16,23,26,27)(18,28,19,21)(7,12)(9,10)(13,18,20,19)(14,23,24,27)(15,26,22,16)(17,21,25,28)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.