One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,6)(4,5)(7,8)(9,10,14,19,15,20,13,18)(11,16,21,17,12,22,23,24)(25,26,28,33,29,32,37,31)(27,30,34,38,35,40,36,39)(2,5)(6,8)(9,11)(10,16)(12,15)(13,23)(14,21)(17,19)(18,24)(20,22)(25,27)(26,30)(28,34)(29,35)(31,39)(32,40)(33,38)(36,37) involution — undirected(1,3)(2,6)(4,7)(5,8)(9,12,15,11)(10,17,20,24)(13,23,14,21)(16,18,22,19)(26,31)(27,34)(28,37)(32,33)(35,36)(38,39)(3,7)(6,8)(9,13,15,14)(10,18,20,19)(11,21,12,23)(16,17,22,24)(26,32)(27,35)(31,33)(34,36)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.