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