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