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