I couldn't find any history specific to this cemetery, but I did find some history of the town Diagonal on IAGenWeb.org
In 1880, the Chicago, Burlington & Quincy (CB&Q) Railroad passed through the town of Goshen (just west of what is now Diagonal). In 1885 the Chicago Great Western Railroad (CGW) came through Knowlton (just north fo what is now Diagonal). At a point approximately two miles from Goshen and Knowlton the tracks crossed diagonally with the CB&Q passing on a creaky bridge with the CGW on firm ground. This crossing became a hub of actitivy with passengers changing trains as needed. Ultimately, the people felt that there was a need to provide lodging and meals for the passengers at this cross. Thus, the town of Diagonal was officially incorporated in 1888 at this crossing.
Originally the newly founded town was called "Hak-a-dady." In February the name of Morton was adopted in honor of Governor O. P. MORTON of Indiana. In March of 1889, the town was re-named Diagonal. The first building was moved from Goshen to Diagonal on April 1, 1889. Soon the townspeople and businesses of Goshen followed, relocating at Diagonal. By 1896, the townspeople of Knowlton began to migrate to Diagonal.
With eight passenger trains a day stopping at Diagonal, the town flourished. As many as 150 people used the facilities in one day. This, of course, brought business into the town as people sought meals, lodging, and livery services.
Currently Diagonal is home to around 300 residents.
This cemetery has an interesting layout, lots of twists and turns and differences in elevation for such a small plot of land. Due to the trees, the coordinates may be slightly off. You are looking for a peanut butter jar and should not have to disturb any stones or vegetation to locate the cache. Please be respectful, do not hunt at night, do not disturb mourners, and leave this peaceful and revered place in good condition. Remember to practice CITO, always. Thank you.