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