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