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