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