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