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)(11,17)(12,20)(13,16)(14,18)(15,21)(19,22)(23,24)(25,26)(27,31)(28,34)(29,37)(30,33)(32,38)(35,40)(36,39)(2,7)(3,4)(9,10,13,16)(11,14,18,17)(12,15,21,20)(19,22,24,23)(25,27,30,28)(26,31,33,34)(29,35,38,36)(32,39,37,40)(1,3,6,4)(2,8,7,5)(11,18)(14,17)(19,24)(22,23)(25,28,30,27)(26,31,33,34)(29,36,38,35)(32,39,37,40)(1,4,6,3)(2,5,7,8)(9,11,13,18)(10,14,16,17)(12,19,21,24)(15,22,20,23)(25,26)(27,34)(28,31)(29,32)(30,33)(35,40)(36,39)(37,38)(1,5)(2,3)(4,7)(6,8)(9,10)(11,14)(12,15)(13,16)(17,18)(19,22)(20,21)(23,24)(25,29)(26,32)(27,35)(28,36)(30,38)(31,39)(33,37)(34,40) involution — undirected(9,12,13,21)(10,15,16,20)(11,19,18,24)(14,22,17,23)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.