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