I stumbled upon this painting by one of those intrepid British artists of the 19th century, William Simpson.
It shows the tile mosaic on the floor of the cave under the Dome of the Rock! Thus far it’s the only visual attestation to it I’ve been able to locate. It’s from 1870.
Simpson’s work is rather well known, including views of the rock within the Dome of the Rock. The Victoria and Albert Museum in London has some of his drawings from his travels in Jerusalem, including a detailed close view drawing from 1869 the one of the mihrabs (the Islamic prayer stands, two of the oldest of which in the world happen to be in the cave in question; note them both in the image above; they flank the staircase that descends into the cave).
There is also an intriguing passage in a book published in 2003, Contested Holiness by Rivka Gonen which I believe paraphrases a description penned around 1881 by Charles Wilson based on his 1860s explorations of the Temple Mount:
Due to the fact that the Jordan-based religious organization called the Waqf (in concert with the Islamic Council and Grand Mufti of Jerusalem) govern the Temple Mount (site of the Dome of the Rock and Al-Aqsa Mosque and former home of both the Second, or Herod’s and the First, or Solomon’s Temple) no archaeological or other investigations are permitted on the the area that contains–because it is composed of–at least 3,000 years of its history. However, there are people who know what there is to know, and who are on top of what trickles, or has been recklessly scooped as the case may be, out of it.
So to get a little expert viewpoint I shared the painting at the top with the folks at the Temple Mount Sifting Project, an amazing archaeology group in Jerusalem sponsored in part by the Ir-David Foundation, but supported by donation and volunteers that has been meticulously examining detritus from the actual Temple Mount that was carelessly removed and discarded by workers under the authority of the Temple Mount-governing Muslim Waqf years ago; from the piles of dirt and rubble they *daily* find revealing artifacts and have in fact discovered historically significant finds from the First and Second Temple Periods that demonstratively embody ancient Jewish presence there. This seal pictured at right and dating from the 700s BCE, is an example: it bears three of the four letters of the Tetragrammatron (the name of G-d), YHW-.
The point-person, Zachi Dvari informed me that the smaller of the two patterns in the cave floor (pictured, again, here) dates from the original construction of the Dome of the Rock–690 CE, or 1,325 years ago.