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