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