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