software for drawing graphs (trees) [duplicate]

Anyone know of an online tool available for making graphs (as in graph theory - consisting of edges and vertices)? I have about 36 vertices and even more edges that I wish to draw. (why do I have so many? It's for pathing in a game)

Only tool available to me right now is MS Paint and it would be very messy.

Edit:

I'm not actually looking for a 'standard' - just some way to neatly draw a set of vertices and edges, preferably without having to write code. I was planning to screenshot the pic and use it in a question on gamedev but I managed to solve the problem for now. Thanks for all the answers. I still prefer GeoGebra because it accessible online, neat, accurate, aligns elements to a grid, has consistent shapes, and has a high degree of customization available.

For drawing graph, the best is TIKZ but it does take some time to study, an alternate is graphviz

Rollbacked:

For drawing 2D geometry, try GeoGebra or Sketchpad (licensed).

For drawing 3D geometry, try Cabri 3d (licensed).

yEd is a free cross-platform application that lets you interactively create nodes and edges via drag and drop, format them with different shapes and styles, and apply various graph layout algorithms to arrange the graph neatly.

Draw.io is really nice and user friendly. It is free and open source. There's a Desktop version available.