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