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