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