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