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