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