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