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