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