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