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