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