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