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