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)(11,13)(12,16)(14,15)(17,21)(18,20)(19,22)(23,24)(25,26,31,35)(27,33,38,29)(28,32,30,34)(36,39,37,40)(1,3,5,8)(2,4,6,7)(12,19)(16,22)(18,23)(20,24)(25,27,31,38)(26,29,35,33)(28,36,30,37)(32,40,34,39)(2,6)(3,8)(10,15)(11,17)(16,22)(18,23)(25,28,31,30)(26,32,35,34)(27,36,38,37)(29,40,33,39)(1,3)(2,7)(4,6)(5,8)(9,11,14,17)(10,13,15,21)(12,18,19,23)(16,20,22,24)(25,27)(26,33)(28,36)(29,35)(30,37)(31,38)(32,39)(34,40)(1,3)(2,4)(5,8)(6,7)(9,12)(10,16)(11,18)(13,20)(14,19)(15,22)(17,23)(21,24)(25,29,31,33)(26,27,35,38)(28,39,30,40)(32,37,34,36)(1,4)(2,8)(3,6)(5,7)(9,13)(10,17)(11,15)(12,20)(14,21)(16,23)(18,22)(19,24)(25,30,31,28)(26,34,35,32)(27,37,38,36)(29,39,33,40)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.