Ajudando.js

const webdriver = require('selenium-webdriver');

const { By, until, keys } = webdriver;

let chrome = require('selenium-webdriver/chrome');
let options = new chrome.Options();

options.addArguments("user-data-dir=c:/Users/Derex/AppData/Local/Google/Chrome/User Data/DC/");
let driver = new webdriver.Builder()
    .forBrowser('chrome')
    .setChromeOptions(options)
    .build();

driver.get('http://www.facebook.com/groups/');

//COM AWAIT
let getLinksGroups = (async () => {
    return new Promise(async resolve => {
        let liDir = await driver.findElement({ css: '.uiList.mam._509-._4ki._4ks' });
        let nLi = await liDir.findElements({ xpath: './li' });
        let nLinks = await Promise.all(nLi.map(async (elem, index) => {
            return await elem.findElements({ css: 'li>ul>li' });
        }))
        return await nLinks;
    })
});

// Com promises
const getLinksGroups2 = () => new Promise((resolve, reject) => {
    driver
        .findElement({ css: '.uiList.mam._509-._4ki._4ks' })
        .then(liDir => liDir.findElements({ xpath: './li' }))
        .then(nLi => Promise.all(nLi
            .map(element => element.findElements({ css: 'li>ul>li' }))))
        .then(resolve)
        .catch(reject);
});

// possivelmente funcione por que o WebElement que
// é devolvido pelo selenium deixa usar o findElements diretamente no retorno do findElement
const talvezFuncioneGetLinkGroups = () => new Promise((resolve, reject) => {
    driver
        .findElement({ css: '.uiList.mam._509-._4ki._4ks' })
        .findElements({ xpath: './li' })
        .then(nLi => Promise.all(nLi
            .map(element => element.findElements({ css: 'li>ul>li' }))))
        .then(resolve)
        .catch(reject);
});

driver.wait(until.elementLocated({ css: '._38my' })).then(() => {
    getLinksGroups().then((asd) => {

    })
});

setTimeout(() => {
    driver.quit();
}, 15000);