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