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