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