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