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