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