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