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