According to my page on that match, 1886 Steinitz - Zukertort Title Match, it took place in 'New York / St.Louis / New Orleans, I-III, 1886'. The '16 Leading Players' illustration was published in the 17 July 1886 issue of The Graphic. The centerpiece of that composite illustration, Steinitz and Zukertort seated at a chess table, could very well have been taken from the match. What other images are available from the 1886 match?
Google image search on '1886 Steinitz Zukertort'
The composite image shown above is based on a technique that I use frequently on my main blog, most recently in a post for Berlin Candidates - Venue (March 2018); 'Call the rows 'A' to 'C' (from top to bottom) and number the images in each row '1' to 'x' (from left to right)'. Two of the images (A3 & B1) show the '16 Leading Players' illustration, other images are from the 1886 match (e.g. A1 & A2), and others are from different Steinitz matches (e.g. C1 & C4).
Given that the 1886 match was the first recognized World Championship, were Steinitz and Zukertort the world's best players? Were the other 14 players also among the best? My page of relevant BCM clippings, 1886 Steinitz - Zukertort : Background, confirms that the match was a direct consequence of the 1883 London Tournament, where Zukertort and Steinitz finished 1st and 2nd. In fact, nine of the '16 Leading Players' finished in the first ten of the 14 players in that event; only Chigorin, who finished 4th, is missing.
Chessmetrics.com has a page that covers the period coinciding with the start of the match, Monthly List: January 1886 rating list. Although the Chessmetrics calculations can't be taken as gospel, they do show 11 of the 16 players in the site's own top-16. The bottom line is that The Graphic's selection is probably as good a list as anyone's.