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