Измените массив полей id,name,picture
на id,name,picture.type(large)
https://graph.facebook.com/v2.8/me?fields=id,name,picture.type(large)&access_token=<the_token>
Результат:
{
"id": "130716224073524",
"name": "Julian Mann",
"picture": {
"data": {
"is_silhouette": false,
"url": "https://scontent.xx.fbcdn.net/v/t1.0-1/p200x200/15032818_133926070419206_3681208703790460208_n.jpg?oh=a288898d87420cdc7ed8db5602bbb520&oe=58CB5D16"
}
}
}