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