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