That is the light sequence for a vessel that is restricted in ability to maneuver not just engaged in diving. Most commercial vessels are equipped to show this sequence of lights.
I know of no ready made lights for personal recreational boats. Just show an around white anchor light and dive flag or make your own.
International Regulations for Preventing Collisions at Sea - Wikipedia, the free encyclopedia
Rule 27 ) A vessel engaged in dredging or underwater operations, when restricted in her ability to manoeuvre, shall exhibit the lights and shapes prescribed in sub-paragraphs (b)(i), (ii) and (iii) of this Rule and shall in addition, when an obstruction exists, exhibit:
1. two all-round red lights or two balls in a vertical line to indicate the side on which the obstruction exists;
2. two all-round green lights or two diamonds in a vertical line to indicate the side on which another vessel may pass;
3. when at anchor, the lights or shapes prescribed in this paragraph instead of the lights or shape prescribed in Rule 30.
(e) Whenever the size of a vessel engaged in diving operations makes it impracticable to exhibit all lights and shapes prescribed in paragraph (d) of this Rule, the following shall be exhibited:
1. three all-round lights in a vertical line where they can best be seen. The highest and lowest of these lights shall be red and the middle light shall be white;
2. a rigid replica of the International Code flag "A" not less than 1 metre (3.3 ft) in height. Measures shall be taken to ensure its all-round visibility.