One vertex per element, one color per generator, with an edge from x to x·s.
(1,2)(3,7)(4,8)(5,6)(9,10)(11,22)(12,17)(13,19)(14,20)(15,30)(16,21)(18,24)(23,39)(25,32)(26,33)(27,34)(28,36)(29,38)(31,37)(35,40) involution — undirected(2,6)(7,8)(9,11,14,12)(10,17,20,22)(13,27,28,40)(15,24,16,26)(18,30,33,21)(19,35,36,34)(23,29,25,31)(32,38,39,37)(1,3,5,4)(2,7,6,8)(9,11,16,26,14,12,15,24)(10,18,30,17,20,33,21,22)(13,23,31,40,28,25,29,27)(19,34,38,32,36,35,37,39)(1,4,5,3)(2,8,6,7)(9,12,14,11)(10,17,20,22)(13,27,28,40)(15,26,16,24)(18,30,33,21)(19,34,36,35)(23,29,25,31)(32,37,39,38)(9,13,14,28)(10,19,20,36)(11,23,12,25)(15,29,16,31)(17,32,22,39)(18,34,33,35)(21,37,30,38)(24,27,26,40)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.