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