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