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