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