"illustration showing" is correct and commonly used in written English.
It is typically used in the context of describing a visual representation, such as a drawing or photograph, that is used to demonstrate or accompany written information. Example: The textbook included an illustration showing the different stages of cell division.
It had a lurid cover illustration showing a barbed fishhook buried in a gleaming apple.
One illustration showing a young lady "Flaunting her broken arm by supporting it in a large red Colcombet silk handkerchief".
And an illustration showing various covers of the magazine's international editions reversed the labels for Norway and the Netherlands.
The New Yorker, February 21 , 1931 P. 9Consternation caused by cigarette illustration showing foreign Legion Bugler using his left hand.
But the story ends on a positive note: the influence of Amelia Bloomer is implied in a blithe illustration showing contemporary young women in bluejeans and bell-bottoms.
An admirer of good advertising art, he was captivated one day by the technical precision of an illustration showing beads of sweat dripping off a beer bottle.
(The book even offers an illustration showing how he might have been dressed during this work and what tools he might have used).
An in-house magazine, The Chatterbox, advertised "Summer at the Institute" with a Saturday Evening Post-style cover illustration showing well-coiffed patients lounging around a pool.
The form, distributed in a Manhattan courtroom on Friday, also included an illustration showing a naked woman lashed to a spit being turned over a fire.
She inscribed her initials in the back of a velvet chair used in one illustration showing an Orientalized portrait of a contemporary Seder.
THE BACK PAGE illustration, showing software billionaire Bill Gates, dressed as John D. Rockefeller, handing a Horatio Alger-like waif a silicon chip.
