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