(setq evil-emacs-state-cursor '("red" box))
I use this for `evil-default-cursor':
#+begin_src emacs_lisp
(defun cofi/evil-cursor ()
"Change cursor color according to evil-state."
(let ((default "OliveDrab4")
(cursor-colors '((insert . "dark orange")
(emacs . "sienna")
(visual . "white"))))
(setq cursor-type (if (eq evil-state 'visual)
'hollow
'bar))
(set-cursor-color (def-assoc evil-state cursor-colors default))))
#+end_src