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