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