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