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