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