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