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