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