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