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