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