XPS 8940 SATA PWR Cable

My XPS 8940 does not have any SATA hard drive. I want to add a SATA hard drive but the power supply does not have any SATA power connector. The service manual page 55 shows components #14 hard-drive power cable connector (SATA PWR). My system shows 8-pin without the black plug as shown in the manual. So I wonder what cable I could use to get power to my SATA drive. If you have such cable / connection, please provide a picture. Thanks.