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