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