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)(11,20)(12,25)(13,19)(14,29)(15,17)(16,23)(18,28)(21,35)(22,30)(24,33)(26,40)(27,32)(31,36)(34,38)(37,39) involution — undirected(1,3,4,7)(2,5,6,8)(9,11,13,22,15,24,14,23)(10,16,29,33,17,30,19,20)(12,21,26,36,28,38,27,37)(18,31,40,35,25,39,32,34)(2,6)(5,8)(10,17)(16,30)(18,25)(19,29)(20,33)(31,39)(32,40)(34,35) involution — undirected(9,12,14,27,15,28,13,26)(10,18,19,32,17,25,29,40)(11,21,23,37,24,38,22,36)(16,31,20,34,30,39,33,35)(9,13,15,14)(10,19,17,29)(11,22,24,23)(12,26,28,27)(16,20,30,33)(18,32,25,40)(21,36,38,37)(31,34,39,35)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.