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