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