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