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