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