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