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