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)(11,18)(12,16)(13,14)(15,17)(19,22)(20,21)(23,24)(25,26)(27,31)(28,32)(29,39)(30,34)(33,37)(35,40)(36,38)(1,2)(3,6)(4,7)(5,8)(9,11,15,12)(10,16,17,18)(13,19,23,21)(14,20,24,22)(25,27)(26,31)(28,37)(29,36)(30,35)(32,33)(34,40)(38,39)(1,3,5,4)(2,6,8,7)(10,17)(14,24)(16,18)(20,22)(27,35)(29,37)(31,40)(33,39)(9,12,15,11)(10,16,17,18)(13,19,23,21)(14,22,24,20)(25,28)(26,32)(27,29)(30,36)(31,39)(33,40)(34,38)(35,37)(1,3,5,4)(2,6,8,7)(9,13)(10,14)(11,19)(12,21)(15,23)(16,20)(17,24)(18,22)(25,29)(26,33)(27,36)(28,35)(30,37)(31,32)(34,39)(38,40)(1,4,5,3)(2,7,8,6)(9,14)(10,13)(11,20)(12,22)(15,24)(16,19)(17,23)(18,21)(25,26)(27,31)(28,38)(29,33)(30,34)(32,36)(35,40)(37,39)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.