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