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