With  
DrawGraph(G, stylesheet = [vertexpadding = 35], showlabels = false)
I get this

But if I wish emphasize the chromatic number, with
COLORS := [red, yellow, cyan, green, coral, blue, magenta, navy, orange, pink, plum, khaki, turquoise];
cn := ChromaticNumber(G, 'col');
for i to cn do
    HighlightVertex(G, col[i], COLORS[i]);
end do;
DrawGraph(G, stylesheet = [vertexpadding = 35], showlabels = false);
I get this

I want bigger vertices, any suggestions? Thanks

Is there any simple way to combine the commands ChromaticNumber(G) and DrawGraph(G), in order to get a vertex coloring of a graph G? Thanks

Is it possible to draw a graph without names for the vertices? I would get something like this.

"What's new in Maple 2020" explain an exciting new option for DrawGraph: layout=interactive, that should allow you to move vertices in the plot. I tried this in the help page opened in a worksheet window and it works.

Unfortunately when I write in a new worksheet the command

with(GraphTheory): with(RandomGraph): G:=RandomGraph(10,25); DrawGraph(G,layout=interactive)

I get the error

"Error, invalid input: GraphTheory:-DrawGraph expects value for keyword parameter [style, layout] to be of type identical(none, bipartite, circle, default, fixed, grid, interactive, network, spectral, spring, spring[constant], tree, user, planar, random), but received plots:-interactive"

Could you help me? Thanks

The definition 
a:=ModularSquareRoot(10,11)
returns
Error, ... because no numbers in Z11 have the square equal to 10. I need, in a procedure, to prevent the error, I mean something like this:
if a<>ERROR then b:=b+1 else c:=c+1 end if
Any suggestions? Thanks