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