Here are some images depicting about 21 Foreign Legion posters. Not all of them are official recruitment posters but most of the known ones used by the Legion are included. I found out that each poster had a print run of about 2,000 and that there were actually only 15 unique posters ever designed with the first created circa 1947. Five posters were designed with photographs and ten were drawings. The drawings were for the most part the work of legionaries and among the more notable artists were Andreas Rosenberg (Legionnaire and then Army painter in the 1950s) and Rudolf Burda (1960s-1980). This makes original posters highly collectable and might fetch up to 500 euros for one in good condition.
Recruitment posters were displayed for years in transit centers where there would likely be a parade of foreigners who just might make the jump into the Legion; these would be the rail stations, ports, airports and cleverly enough–the police stations (gendarmeries). (I remember seeing a Legion poster in the Police Station in Calais when I was pulled off the train for a random search and questioning in 1982.) Nowadays the internet seems to be one of the more effective recruitment techniques. Unlike the other French military services the Legion kept their posters very simple and usually made no reference to exotic locations as an enticement to enlist. The originals were printed by civilian printers in Paris and Marseilles but are now produced by the folks at Kepi Blanc Magazine. They were made in two sizes with the large 1.5m X 1.5m appearing in the transit centers and the smaller ones .9m X .7m or .5m in other locations. If you can’t find an original Foreign Legion recruitment poster you might have better luck finding a poster created for the annual Camerone celebrations in the various regimental centers.
NOTE: This information came mostly from issue #03 of Soldats de la Légion étrangère by Hachette. The images were from multiple locations on the internet especially Pintrest.