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)(11,12)(13,16)(14,15)(17,18,21,23)(19,24,22,20)(26,30)(27,33)(28,36)(38,40)(9,11,14,13)(10,12,15,16)(17,19)(18,20)(21,22)(23,24)(26,30)(31,34)(32,37)(38,40)(2,3)(6,7)(10,15)(12,16)(17,20,21,24)(18,22,23,19)(25,26)(27,34)(28,32)(29,30)(31,33)(35,40)(36,37)(38,39)(1,3,5,2)(4,7,8,6)(9,12,14,16)(10,11,15,13)(17,20)(18,19)(21,24)(22,23)(25,27)(26,31)(28,35)(29,33)(30,34)(32,38)(36,39)(37,40)(1,4,5,8)(2,6,3,7)(9,13,14,11)(10,16,15,12)(17,18)(19,20)(21,23)(22,24)(25,28,29,36)(26,32,30,37)(27,35,33,39)(31,38,34,40)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.