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