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