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