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