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