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