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