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