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