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