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