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)(11,15)(12,18)(13,21)(14,16)(17,20)(19,24)(22,23)(25,26,31,33)(27,35,37,32)(28,30,39,40)(29,34,36,38)(2,5)(6,7)(9,11,14,20)(10,15,16,17)(12,21,23,19)(13,22,24,18)(25,27,31,37)(26,32,33,35)(28,38,39,34)(29,30,36,40)(10,16)(11,20)(18,22)(19,21)(26,33)(28,39)(32,35)(34,38) involution — undirected(1,2)(3,6)(4,5)(7,8)(9,11)(10,17)(12,21)(13,22)(14,20)(15,16)(18,24)(19,23)(25,28)(26,30)(27,34)(29,32)(31,39)(33,40)(35,36)(37,38) involution — undirected(1,2)(3,7)(4,5)(6,8)(9,12)(10,18)(11,21)(13,15)(14,23)(16,22)(17,24)(19,20)(25,29)(26,34)(27,30)(28,32)(31,36)(33,38)(35,39)(37,40) involution — undirected(1,3,4,8)(2,6,5,7)(9,13,14,24)(10,19,16,21)(11,22,20,18)(12,17,23,15)(25,30)(26,28)(27,36)(29,37)(31,40)(32,38)(33,39)(34,35)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.