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