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