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