Each plane can be plotted as a parameterized surface.
In particular, x=y, can be parameterized as:
x=u
y=u,
z=v
where u and v belong to some intervals.
Example:
using PlotlyJS
ul= range(-1, 1, length=10)
vl= range(0, 0.75, length=8)
u= [s for t in vl, s in ul]
v= [t for t in vl, s in ul]
pl= Plot(surface(x=u, y=u, z=v, colorscale=[[0, "#ADD8E6"], [1, "#ADD8E6"]],
showscale=false),
Layout(width=500, height=400, scene_camera_eye=attr(x=1.95, y=1, z=0.75)))
