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