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