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