I ran across a helpful site recently called draw.io that allows you to build flow charts and other diagrams pretty easily. It also ties in nicely with Google Drive and Dropbox so you can get your designs anywhere. I ended up using the site to visualize some of my DNA matches, specifically matches on certain lines in my family tree. It worked nicely and allowed me to see how exactly we’re connected and what information may be gleaned from those matches (i.e., Y-DNA lines, etc.)
Here are my three designs, in the following order. I visualized my Zalewski cousin tests, my Corrigan cousin tests, my Thielke cousin tests, and my Last cousin tests. The last two are on my maternal side and sort of overlap. I have some other lines to do, yet. Click the images for a larger version.