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