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