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