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