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