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