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