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)(27,32)(28,37)(29,33)(30,40)(31,34)(35,38)(36,39)(1,3)(2,5)(4,7)(6,8)(9,11)(10,15)(12,19)(13,21)(14,20)(16,23)(17,18)(22,24)(25,27,31,36)(26,32,34,39)(28,33,38,40)(29,35,30,37)(3,7)(5,8)(9,12,14,13)(10,16,17,22)(11,19,20,21)(15,23,18,24)(25,28,30,32,31,38,29,39)(26,27,33,37,34,36,40,35)(3,7)(5,8)(10,17)(11,20)(16,22)(19,21)(25,29,31,30)(26,33,34,40)(27,35,36,37)(28,32,38,39)(2,6)(5,8)(9,13,14,12)(10,16,17,22)(11,21,20,19)(15,23,18,24)(27,36)(28,38)(32,39)(35,37)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.