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