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