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