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)(11,16)(12,15)(13,14)(17,18,21,19)(20,23,24,22)(25,26,30,31)(27,32,35,39)(28,36,38,29)(33,34,37,40)(2,4)(3,8)(9,11)(10,15)(12,14)(13,16)(17,18,21,19)(20,22,24,23)(26,31)(29,36)(32,39)(34,40)(1,3,5,8)(2,6,4,7)(9,10,14,13)(11,15,12,16)(17,19,21,18)(20,23,24,22)(25,27)(26,32)(28,37)(29,34)(30,35)(31,39)(33,38)(36,40)(1,3)(2,6)(4,7)(5,8)(9,12,14,11)(10,15,13,16)(17,20,21,24)(18,22,19,23)(25,28)(26,29)(27,33)(30,38)(31,36)(32,40)(34,39)(35,37)(1,4,5,2)(3,7,8,6)(9,13,14,10)(11,15,12,16)(25,29)(26,28)(27,34)(30,36)(31,38)(32,37)(33,39)(35,40)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.