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