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