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)(11,15)(12,18)(13,17)(14,16)(19,22)(20,21)(23,24)(25,26)(27,30)(28,32)(29,33)(31,34)(35,38)(36,37)(39,40) involution — undirected(2,3)(6,7)(9,11,14,18)(10,15,16,12)(13,19,23,21)(17,22,24,20)(25,27)(26,30)(28,35)(29,34)(31,33)(32,38)(36,39)(37,40)(1,2,5,3)(4,6,8,7)(10,16)(11,18)(17,24)(19,21)(27,34)(30,31)(35,40)(38,39)(1,3,5,2)(4,7,8,6)(9,11)(10,12)(13,21)(14,18)(15,16)(17,22)(19,23)(20,24)(25,27)(26,31)(28,35)(29,34)(30,33)(32,39)(36,38)(37,40)(1,4,5,8)(2,6,3,7)(9,12)(10,11)(13,22)(14,15)(16,18)(17,21)(19,24)(20,23)(25,28)(26,32)(27,35)(29,37)(30,38)(31,39)(33,36)(34,40)(9,13,14,23)(10,17,16,24)(11,19,18,21)(12,20,15,22)(25,26)(27,30)(28,36)(29,33)(31,34)(32,37)(35,39)(38,40)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.