yes it is possible to do it simply creating a second traffic-group (traffic-group-2) and forcing device 2 (standby unit) as the default device for traffic-group-2. You can follow this guide to do that: https://techdocs.f5.com/kb/en-us/products/big-ip_ltm/manuals/product/bigip-device-service-clustering...
After that you have to move the virtual IP you want to be active on traffic-group-2. The following article describe how to do it: https://my.f5.com/manage/s/article/K53040085
Please notify that if you have APM provisioned, APM is NOT supported in an Active-Active configuration.
If your problem is the high CPU utilization, moving to an Active-Active could be seen as a good solution and maybe you can think that you can add more services because CPU utilization has decreased; take care that an outage of one peer in that scenario will cause a BIG problem.
While I create a second traffic-group (traffic-group-2) How should I set a default device in that group, Which failover order using to configure "perffer order or Load aware" (device 1 and device2).
since you want to have as long as possible device 1 active for traffic-group-1 and device 2 for traffic-group-2 you need to configure a preferred order and also auto failback as descripted here : How to configure Auto failback for an HA Group (f5.com)