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