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