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