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