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