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