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