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