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