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