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