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