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