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