app/views/devise/shared/_links.erb
<%- if controller_name != 'sessions' %>
<%= link_to "Login", new_session_path(resource_name) %><br />
<% end -%>
<%- if devise_mapping.omniauthable? %>
<%- resource_class.omniauth_providers.each do |provider| %>
<%= link_to "Login with #{provider.to_s.titleize}", omniauth_authorize_path(resource_name, provider) %><br />
<% end -%>
<% end -%>