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