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