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