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