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