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