app/views/devise/shared/_social.html.erb
<div class="social">
<%= link_to "#{social_action } with Twitter",
user_omniauth_authorize_path(:twitter), class: "btn", id: "twitter-button" %>
<%= link_to "#{ social_action } with Facebook",
user_omniauth_authorize_path(:facebook), class: "btn", id: "facebook-button" %>
<%= link_to "#{ social_action } with Google",
user_omniauth_authorize_path(:google_oauth2), class: "btn", id: "google-button" %><br />
<% if controller_name == "registrations" %>
Already have an acccount? <%= link_to "Log in", new_session_path(resource_name) %>
<% end %>
</div>