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