An example of indicator, that draws the saw by the High and Low prices, the DRAW_COLOR_ZIGZAG drawing style is used.

The color, thickness and style of zigzag lines are changed randomly every N ticks. Note, that initially there are 8 colors set for the plot1 graphical plotting (with the DRAW_COLOR_ZIGZAG style) using the #property compiler directive. Then, in the OnCalculate() function the color is chosen at random from 14 colors stored in the colors[] array.

The N parameter of indicator is made as external so that you can adjust it manually (the Inputs tab of indicator properties dialog box).

See also The Drawing Styles in MQL5 article.