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