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