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