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