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