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