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