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