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