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