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