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