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)(11,13)(12,20)(14,15)(16,18)(17,21)(19,22)(23,24)(25,26,32,30)(27,35,29,33)(28,34,31,36)(37,40,38,39)(1,2)(3,6)(4,7)(5,8)(9,11)(10,13)(12,19)(14,18)(15,16)(17,23)(20,22)(21,24)(25,27,32,29)(26,33,30,35)(28,38,31,37)(34,40,36,39)(10,15)(11,18)(12,21)(22,23)(25,28,32,31)(26,34,30,36)(27,37,29,38)(33,39,35,40)(1,3,5,4)(2,6,8,7)(9,11)(10,16)(12,19)(13,15)(14,18)(17,22)(20,23)(21,24)(25,29,32,27)(26,35,30,33)(28,38,31,37)(34,40,36,39)(1,4,5,3)(2,7,8,6)(9,12)(10,17)(11,19)(13,23)(14,21)(15,20)(16,22)(18,24)(25,30,32,26)(27,35,29,33)(28,34,31,36)(37,39,38,40)(9,13,14,16)(10,11,15,18)(12,22,21,23)(17,24,20,19)(25,31,32,28)(26,36,30,34)(27,38,29,37)(33,40,35,39)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.