For the case of just one space dimension we can draw a 2D picture space-time. These space-time diagrams are often helpful in understanding and resolving questions about special relativity, but the way they look depends on the choice of which observer’s world line matches the vertical axis. So I have made an applet which allows the same history to be viewed and animated from the perspectives of several different observers.

See https://qpr.ca/math/applets/SRSim/index.htm