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