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