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