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