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)(11,13)(12,20)(14,15)(16,22)(17,18)(19,24)(21,23)(27,28)(31,32)(35,36)(38,39)(2,7)(3,4)(9,11)(10,13)(12,19)(14,17)(15,18)(16,21)(20,24)(22,23)(25,26,30,34)(27,31,28,32)(29,33,37,40)(35,38,36,39)(1,3,6,4)(2,8,7,5)(10,15)(11,17)(16,20)(19,23)(25,27,30,28)(26,31,34,32)(29,35,37,36)(33,38,40,39)(1,4,6,3)(2,5,7,8)(9,10)(11,18)(12,20)(13,17)(14,15)(16,22)(19,21)(23,24)(25,26)(27,31)(28,32)(29,33)(30,34)(35,38)(36,39)(37,40)(1,5)(2,3)(4,7)(6,8)(9,12,14,22)(10,16,15,20)(11,19,17,23)(13,21,18,24)(25,28,30,27)(26,32,34,31)(29,36,37,35)(33,39,40,38)(9,13,14,18)(10,17,15,11)(12,21,22,24)(16,23,20,19)(25,29,30,37)(26,33,34,40)(27,35,28,36)(31,38,32,39)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.