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