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