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