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