Common style attributes can be edited from the Format Bar. You can change colors, enable a shadow or change the font, among other options:
More detailed style controls are available from the Inspector Panel. These Inspectors are style related (the others are not):
Graphic
More information on the Graphic Inspector.
Form
More information on the Form Inspector.
Image
More information on the Image Inspector.
Lettering
More information on the Lettering Inspector.
Text
More information on the Text Inspector.