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