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