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