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