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)(11,17)(12,20)(13,22)(14,19)(15,16)(18,23)(21,24)(25,26,30,34)(27,31,37,32)(28,33,39,29)(35,36,38,40)(1,3,4,7)(2,5,6,8)(10,16)(13,23)(17,20)(19,21)(25,27,30,37)(26,31,34,32)(28,38,39,35)(29,36,33,40)(1,2)(3,5)(4,6)(7,8)(9,11,15,12)(10,17,16,20)(13,19,23,21)(14,18,24,22)(25,27)(26,32)(28,35)(29,36)(30,37)(31,34)(33,40)(38,39)(1,3)(2,5)(4,7)(6,8)(9,12,15,11)(10,17,16,20)(13,21,23,19)(14,18,24,22)(25,27)(26,31)(28,35)(29,40)(30,37)(32,34)(33,36)(38,39)(1,2)(3,5)(4,6)(7,8)(9,13,15,23)(10,18,16,22)(11,19,12,21)(14,17,24,20)(25,28)(26,33)(27,35)(29,34)(30,39)(31,36)(32,40)(37,38)(9,14,15,24)(10,19,16,21)(11,18,12,22)(13,17,23,20)(25,29,30,33)(26,28,34,39)(27,36,37,40)(31,38,32,35)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.