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