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