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