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