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