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