First step to get the angle of the node, get the center of the circumference
So i get 3 points of the 3rd first nodes to get it:

AX= cy.nodes()[0]._private.position.x   
AY= cy.nodes()[0]._private.position.y   
BX= cy.nodes()[1]._private.position.x   
BY= cy.nodes()[1]._private.position.y   
CX= cy.nodes()[2]._private.position.x   
CY= cy.nodes()[2]._private.position.y   

var yDelta_a = BY - AY 
var xDelta_a = BX - AX; 
var yDelta_b = CY - BY; 
var xDelta_b = CX - BX;
var aSlope = yDelta_a / xDelta_a; 
var bSlope = yDelta_b / xDelta_b;

//Get center circumference
coordCentroCircunferenciaX = (aSlope*bSlope*(AY - CY) + bSlope*(AX + BX) - aSlope*(BX+CX) )/(2* (bSlope-aSlope) );
coordCentroCircunferenciaY = -1*(coordCentroCircunferenciaX- (AX+BX)/2)/aSlope +  (AY+BY)/2;     

Then iterate through the nodes getting the angles:

for (i = 1;i< cy.nodes().length; i=i+1) { //starts nodes loop
    let nodo=cy.nodes()[i];
    array.push(nodo._private.data.name);

    //get the node position(x,y)
    nodox=nodo._private.position.x
    nodoy=nodo._private.position.y

Now with 3 points: center circumference , node position and another point in the x axis

C = { x: coordCentroCircunferenciaX, y: coordCentroCircunferenciaY };
A = { x: nodox, y: 0 };
B = { x: nodox,y:nodoy  };

Then i get the angle with this function:

function find_angle(A,B,C) {
    var AB = Math.sqrt(Math.pow(B.x-A.x,2)+ Math.pow(B.y-A.y,2));    
    var BC = Math.sqrt(Math.pow(B.x-C.x,2)+ Math.pow(B.y-C.y,2)); 
    var AC = Math.sqrt(Math.pow(C.x-A.x,2)+ Math.pow(C.y-A.y,2));
    return Math.acos((BC*BC+AB*AB-AC*AC)/(2*BC*AB))*(180/Math.PI);   
}

Finally this is the angle with the center of the circumference:

let angulo=Math.round(find_angle(A,B,C))

So with this angle i can get this effect to rotate node labels: