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