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