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