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