You can change the color of the cell when it is hovered or selected by modifying the theme that you are using. You can achieve this by changing the repository items, assigned to the SchedulerCellElement.MouseOver and SchedulerCellElement.Selected states. Please refer to the attached image.
For more information about using Visual Style Builder, please refer to this help section.
the Telerik team
Q1’11 SP1 of RadControls for WinForms is available for download; also available is the Q2'11 Roadmap for Telerik Windows Forms controls.