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