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