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